This invention relates to a high-strength, austenitic, stainless steel, and to methods of its production.
There is great use of austenitic stainless steels, especially in the petrochemical industry where their properties are essential. Ideal properties include high corrosion and pitting resistance, good weldability and elongation, good low-temperature impact resistance, high proof strength and high tensile strength.
These ideal metallurgical properties can be summarised as follows:
(a) PREN(=%Cr+3.3Mo+16 N) greater than 50
(b) 0.2% proof strength= greater than 400 N/mm2 
(c) critical pitting temperature  greater than 70xc2x0 C.
(d) good weldability.
Such steels have been the object of much attention and research. Many attempts have been made to achieve all the properties listed but up to this time it was widely believed that they were basically incompatible, especially in the cast form, and could only be achieved to some acceptable degree in the wrought form.